1. Field of Invention
This invention relates to steering and brake arrangements for vehicles such as tractors. More specifically, this invention relates to a steering and brake arrangement which comprises a steering column support structure which carries a steering wheel of the vehicle, two brake pedals and one master cylinder for operating a cardan brake or front axle brakes, a left rear brake and a right rear brake of the vehicle.
2. Description of Related Art
In modern tractors space is at a premium and therefore there is a requirement to provide a compact steering wheel and brake pedal support arrangement which can be located conveniently in the tractor cab for the vehicle operator.
The use of a compact steering and brake arrangement is also important on tractors where the driving seat can rotate through 180 degrees to a reverse driving position in order to provide good clearance for the rotation of the seat.
UK patent application No. 1109306.9 discloses a steering and brake arrangement for two steering brakes. This application discloses a single circuit brake arrangement. For two steering brakes, two master cylinders are needed to control either a left or a right wheel rear brake
The left and right rear wheels of modern tractors are usually provided with separate left and right brakes which are activated by the operator by respective foot pedals to assist with steering. The tractor is further provided with a cardan brake which is activated together with both left and right brakes when both foot pedals are depressed together.
DE9204417 discloses a hydraulic brake arrangement in which two foot pedals are connected to two separate rear brakes and a front axle brake. The front axle brake is connected by a switch valve to both foot pedals which in turn operates two respective hydraulics. The switch valve activates when sufficient pressure is applied, that is when both cylinders are depressed. When one cylinder is depressed there is not enough pressure to enable the front brake to be activated and as a result only one of the rear brakes is activated.
However, switch valves suffer from wear and tear and may start to open under lower pressures, that is when only one foot pedal is depressed. This can lead to safety issues as a non reliable front brake may work in addition to a rear brake when it is not meant to. For example, the operator may only wish to apply one rear brake to steer around a corner, but if the front brake is also inadvertently applied there may be consequences if travelling at speed